A lactose-positive strain of Salmonella litchfield was isolated from periproctal absess. The lactose-positive character of the strain was attributed to a plasmid with a molecular weight of about 130 megadaltons. This plasmid, pRY82, was conjugally nontransmissible but was mobilized by plasmid pTH10. Resistance to chloramphenicol, streptomycin, sulfamethoxazole, tetracycline and potassium tellurite as well as inhibition of development of bacteriophages T7 and lambda were mediated by pRY82. It was suggested that pRY82 is a member of the H2 incompatibility group. During the course of the test for incompatibility, recombination between pRY82 and R478 DNAs occurred in high frequency to form new plasmids mediating lactose-utilization and resistance to kanamycin.
An immunostimulatory agent partially purified from the aqueous phase of phenol-water extracts of BCG was studied for its anti-tumor effects in mice. The agent exerted marked suppressive effects on sarcoma 180 inoculated into ICR mice and caused extensive hemorrhagic necrosis and regression and high incidence of complete cure of Meth A fibrosarcoma established in BALB/c mice as did a reference Escherichia coli lipopolysaccharide (LPS), although much higher doses of the agent than those of LPS were used. The antitumor effects of the agent were accompanied with considerable loss of body weight of test animals, but the weight loss was less than that caused by the reference LPS and ceased when the drug administration was stopped. A synergistic anti-Meth A tumor effect was noted in combined use of the agent and Nα-(N-acetylmuramyl-L-alanyl-D-isogulutaminyl)-Nε-stearoyl-L-lysine under the experimental conditions where each compound was scarcely active.